kayakita,
I am in Arkansas and I know the feeling about the temps. Highs only for the next 6 days: 57, 39, 54, 31, 42, 53
With regards to the raised beds, do you have a landfill nearby? I have the same soil composition and I buy compost from the landfill for $10 a truckload. I am not sure about how the citrus would work out because of loose soil, but I can tell you other plants really love the setup. I highly recommend the raised beds. In the following setup, I tilled the area, put down a layer of compost and tilled the area again. I then put down a 1" layer of Canadian Peat moss. I raised the rest of the way up with compost and dressed it with mulch. I will say raised beds are more work. The compost settles and will have to be re-raised. I lost about 1" - 1.5" of depth in a year.
See the growth in my bed, that at the time was almost a year old.
http://www.ubcbotanicalgarden.org/forums/showpost.php?p=168166&postcount=15
The mums started out as 6" plants.